The present disclosure relates to subject matter contained in Japanese Patent Application No. 6-130179 (filed on Jun. 13, 1994) and Japanese Patent Application No. 7-58515 (filed on Mar. 17, 1995), which are expressly incorporated herein by reference in their entireties.
1. Field of the Invention
The present invention relates to an endoscope having a tool guide member for changing the direction of projection of a bioptic forceps or other tool for an endoscopic procedure (hereinafter referred to as "tool"), which is projected outwardly from the distal end of the insert part of the endoscope.
2. Description of the Prior Art
The tool guide member of an endoscope is generally disposed at the distal end of the insert part of the endoscope so as to be pivotable about a shaft, and pivoted by a control wire which is remote-controlled.
FIG. 7 shows the distal end of an insert part of a conventional endoscope, with a plastic cover detached therefrom. The endoscope has a distal end block 51 which is provided at the distal end of the insert part. The distal end block 51 has a viewing window 52 and an illuminating window 53, which are provided in one of side portions of the distal end block 51. A tool guide member 54 is provided in the other side portion to change the direction of projection of a tool, which is projected sidewardly.
The distal end block 51 has a pair of inner and outer walls 55 and 56 which are in contact with both side surfaces of the tool guide member 54. The tool guide member 54 pivots about a shaft 57 which is inserted at both ends thereof into the two walls 55 and 56.
The outer wall 56 is provided with a relatively large cut portion 59 so as not to interfere with a stopper pin 58 which projects from the side surface of the tool guide member 54. A control wire 60 for pivoting the tool guide member 54 by remote control extends through the cut portion of the outer wall 56, and the distal end of the control wire 60 is connected to the side surface of the tool guide member 54.
In the endoscope having the above-described structure, however, a relatively large gap is formed between the cut wall portion 59 and the control wire 60. Accordingly, as shown in FIG. 8, when a tool 100 is to be projected outwardly along the tool guide member 54 from a tool inserting channel 62, the distal end of the tool 100 may enter the gap between the control wire 60 and the cut wall portion 59 to get caught on the control wire 60, resulting in a failure to control the tool 100. Reference numeral 61 in FIG. 8 denotes a plastic cover which covers the distal end block 51.
There is a conventional endoscope in which the outer wall 56 is formed to extend as close to the control wire 60 as possible, thereby minimizing the gap (Japanese Patent Unexamined Publication (KOKAI) No. 4-218134). The conventional technique can cope with the above-described problem to a certain extent. However, when a tool with a thin distal end is used, it is likely that the thin distal end will get caught in the gap between the control wire 60 and the outer wall 56.
There is another conventional endoscope in which the control wire is disposed at the inside of the inner wall so as to be separate from the tool guide member (Japanese Utility Model Unexamined Publication (KOKAI) No. 54-90088). With this arrangement, however, the control wire lies between the viewing window and the tool guide member, and the tool guide member lies correspondingly far away from the viewing window. As a result, the tool guide member can be seen only at an edge of the observation field of view. Therefore, the tool guiding performance deteriorates to a considerable extent.